The 19^th seeds prevailed in a thrilling duel with Czech Republic’s Ondrej Perusic and David Schweiner, winning 21-14, 15-21, 15-13 in the specially-built arena at Meia Praia in the Brazilian coastal city.

It will be the first quarter-final appearance of the season for Krattiger and Beeler.

"We served really well and put a lot of pressure on them," Beeler said.

"We had a good start in the third set and that lead gave us some confidence to be better in the last points near the end.

"The season was not going so well for us, so it’s really important that this time we managed to play well and win important matches."

Next up for the Swiss duo are Norway's Anders Mol and Christian Sørum, who beat Mexico's Juan Virgen and Lombardo Ontiveros 24-22, 21-19.

World champions Evandro Gonçalves and Andre Loyola of Brazil are also through to the quarter-finals as they defeated Cubans Sergio Gonzalez and Diaz Nivaldo 21-18, 21-19.

Standing between them and a place in the semi-finals are Canada’s Sam Pedlow and Sam Schachter, who advanced after Argentina’s Nicolás Capogrosso and Julian Azaad forfeited due to injury.

The two other quarter-final match-ups will see The Netherlands’ Alexander Brouwer and Robert Meeuwsen face Brazil’s Vitor Felipe and Guto Carvalhaes, and Poland’s Piotr Kantor and Bartosz Losiak meet the Dutch pairing of Christiaan Varenhorst and Jasper Bouter.

In the women’s tournament, Czech Republic’s Marketa Slukova and Barbora Hermannová won all three of their matches today to reach the quarter-finals.

Having lost their opening Pool D match yesterday against Slovakia’s Andrea Strbova and Natalia Dubovcova, they started today by overcoming Finland’s Niina Ahtiainen and Riikka Lehtonen 21-13, 21-12.

That set up a first-round encounter with Austria’s Lena Plesiutschnig and Katharina Schützenhöfer, who they beat 21-9, 21-11 before defeating top-seeded home favourites Barbara Seixas and Fernanda Alves 21-19, 21-17.

"It had been a while since we had last lost our first match on pool play, but I think it made us stronger," Hermannová said.

"We learned from the mistakes we made in the first match.

"Against Brazil, it was always tight."

Slukova and Hermannová will now go up against Canadians Heather Bansley and Brandie Wilkerson, who advanced automatically to the quarter-finals with their opponents, Russians Nadezda Makroguzova and Svetlana Kholomina, unable to play due to injury.

Among the other six teams that have qualified for the quarter-finals are Brazil’s Agatha Bednarczuk and Duda Lisboa and Maria Elisa Antonelli and Carolina Solberg, and Czech Republic’s Kristyna Kolocova and Michala Kvapilová.

They are joined by Germany’s Victoria Bieneck and Isabel Schneider and Karla Borger and Margareta Kozuch, and Switzerland’s Anouk Vergé-Depré and Joana Heidrich.

Borger and Kozuch also had to go through three matches today and the last of them was an all-German duel with Julia Sude and Chantal Laboureur, which they won 23-21, 24-26, 15-8.

The quarter-finals and semi-finals in both the men's and women's events are scheduled for tomorrow.

The medal matches are due to take place on Sunday (May 20).